Sampling devices are used in various applications such as the chemical, food, pharmaceutical and energy industries to collect a sample of process media for testing and/or analysis. These sampling devices are usually in the form of a valve that when opened is capable of extracting liquids, gases or other process media from an attached pipeline or conduit. Some types of sampling devices require process interruption where the system is temporarily shut down and a representative sample is taken. Various types of process media may be sampled including water, fuel, beverages as well as toxic substances. Danger of harmful spills is not present when innocuous media is sampled. However, when dangerous or expensive media is sampled, spillage and waste become problematic.
Certain sampling devices permit the removal of sampling media from a conduit into a receptacle via a connection pipe or tube. When corrosive or abrasive material is being sampled, this environment allows for the corrosive effects of the material to compromise the integrity of the system. This limits the number of strokes or cycles in the life of the valve. In addition, when the process media is corrosive material, the valve utilized in the sampling system also becomes susceptible to corrosion. This condition is exasperated when the system undergoes temperature elevations and fluctuations.
Various types of configurations may be employed to try and limit the corrosive effects on the operation of the valve. One configuration utilizes a lining on the valve spindle with a fully fluorinated Fluoropolymer like Teflon® and a Teflon® seal. The Teflon® materials referred to herein are fully fluorinated fluoropolymers including, but not limited to PTFE, PFA, TFM or NXT. However, this makes it difficult to achieve a perfect seal because of the thermal expansion of the Teflon® material due to elevated or fluctuating temperatures. In addition, the Teflon® to Teflon® seal creates unwanted wear resulting from the linear movement of the spindle. Accordingly, there is a need for a valve sampling system that accommodates adequate sealing characteristics in a corrosive process media environment at elevated and fluctuating temperatures. The above-referenced drawbacks and others are overcome by the present invention described herein with reference to the detailed description, drawings and appended claims.